Characterization of Multilayered Structures Using a FEGSEM and X-Ray Microanalysis

Abstract

Microelectronic processes now involve multilayer structures of different materials. It is important to control accurately the thickness and composition of these materials during their processing. The determination of these two physical parameters are usually performed by Elastic Recoil Detection (ERD), by Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). However, these techniques are not suitable for analysis on a routine basis. In this context, a quantitative procedure based on EDS X-ray microanalysis in the Scanning Electron Microscope has been developped because of its availability and its speed of analysis. However, this technique requires several measurement of K ratio taken at different voltages which is time consuming. With the advent of Field Emission Gun Scanning Electron Microscopes (FEGSEM), X-ray line scans taken at low electron beam voltage with an EDS system may be an alternative. In this paper, preliminary results using this technique on multilayered materials are presented.To investigate this characterization technique, a AlSiCu(200 nm)/TiN(95 nm)/Ti(40 nm) multilayer metallization structure deposited on Si substrate was used. EDS X-ray line scans were obtained with a Hitachi S-4500 FEGSEM coupled with a Link ISIS 300 EDS system.